Table 5.

Summary bone health

				Association of protein/effect (in RCT)
			Number of participants (age) Men (M), Women (W)					Rating A B C
Exposure/Intervention	Outcome variable	Study		Total	Animal	Vegetable	A/V ratio		Strength of evidence (strong, medium, low) Suggestive No conclusion
Protein E% in tertiles	Bone loss	Cohort (41)	560 (14–40 years) W	NS	NS	NS	NA	C	No conclusion
Protein E% in tertiles and A/V ratio	Bone loss	Cohort (42)	1,035 (>65 years) W	NS	NA	NA	POS	C
Total protein intake (g/kg BW) and protein E% in quartiles	Bone loss	Cohort (43)	615 (69–97 years) M and W	INVERSE INVERSE	INVERSE INVERSE	NA NA	NA NA	C
Total protein intake in g/day or g/kg BW		Review and meta-analysis (44):						B
	Bone loss	Cohort		NS
	BMD	RC trials		POS
Protein (g/kg BW)	Fracture	Cohort (45)	36,217 (40–65 years) W	NS	NA	NA	NA	B	No conclusion
Energy adjusted per 1,000 kcal of total, animal, and vegetable protein in tertiles:
Low calcium				POS	POS	INVERSE	NA
High calcium				NS	NS	NS	NA
Protein (g/day) in tertiles for total, animal and vegetable	Fracture	Cohort (46)	3,656 (mean 55 years) M and W	NS	NA	NA	NA	B
Low calcium				NS	POS	NS	NS
High calcium				NS	INVERSE	NS	NS
Protein E% in tertiles and A/V ratio	Fracture	Cohort (42)	1,035 (> 65 years) W	NS	POS	NS	POS	C
Total protein intake in g/day or g/kg BW	Fracture	Review and meta-analysis (44): RC trials		NS				B
Dietary acid load (including protein)	Osteoporosis	Review and meta-analysis (47)		NS				C	No conclusion
High and usual protein intake combined with high and low sodium diet High and low protein intake combined with high and low calcium diet	Calcium- and bone metabolism Calcium- and bone metabolism	Randomized cross-over trial (48) Randomized cross-over trial (49)	24 (50–67 years) W 27 (50–69 years) W	High protein-high sodium: increased calcium loss lead to increased bone resorption. Cannot separate protein and sodium effects POS interaction (high protein increased calcium retention when calcium intake was low)				B A	No conclusion